Update clap to v4

[coolreader18]

Been a long time coming, but it wasn't too hard in the end. Also fixed some parity issues that came up while trying to figure out the correct behavior.

closes #4445 #3512

[youknowone]

This test is the major blocker:

======================================================================
FAIL: test_scriptdecode (test.test_quopri.QuopriTestCase.test_scriptdecode)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/RustPython/RustPython/pylib/Lib/test/test_quopri.py", line 207, in test_scriptdecode
    self.assertEqual(cout.splitlines(), p.splitlines())
AssertionError: Lists differ: ["Her[17 chars]ecial=3D20", '', '=3DA1=3DA2=3DA3=3DA4=3DA5=3D[515 chars]un!'] != ["Her[17 chars]ecial ", '', '¡¢£¤¥¦§¨©', 'ª«¬\xad®¯°±²³', '´µ[134 chars]un!']

First differing element 0:
"Here's a bunch of special=3D20"
"Here's a bunch of special "

Diff is 909 characters long. Set self.maxDiff to None to see it.

[coolreader18]

Yeah, I opened https://github.com/clap-rs/clap/discussions/5747 about it. I think it'll ultimately require patching clap in some way.

[youknowone]

see also: https://github.com/clap-rs/clap/issues/3903